A glyph can be thought of as a program that, given a resolution produces an opacity mask that can be used to draw the glyph at that resolution.
Such a program creates control points for spline curves that define areas to be drawn using some foreground color. The exact position of these control points may vary according to the final resolution, because it might be desirable to align some parts of the curves with the final drawing grid.
While it is possible to write code for generating these control points directly in Common Lisp, doing so is time consuming, error prone, and the result is difficult to maintain.
We are thinking that it might be possible to represent the computations of these control points interactively, as a combination of a small set of functions applied to the coordinates of the grid and the resolution.
The application should allow the user to modify the final resolution interactively so as to observe the final result as a function of that resolution. It should also allow for zooming (independently of the resolution) for a detailed view of the position of the control points.
Most of the application logic should be extracted into a library for manipulating glyphs and fonts.